With the advent of higher performance gas turbine engines and advanced combustors, it has become necessary to increase the size of the combustor and air swirlers to accommodate the increase in swirler air to control smoke emissions. This has increased the complexity and problems associated with ignition. Of particular note is the fact that since the distance between the fuel nozzle orifice and the inner wall of the swirler is moving further apart, the problem becomes even more difficult and complex. Hence, where, in heretofore fuel nozzles, the distance between the primary circuit orifice in a two circuit fuel nozzle inherently lent itself to good ignition performance, the larger combustors inherently dictate against good ignition performance.
This invention addresses the ignition problem associated with advanced combustor that utilize a primary and secondary circuit of the type disclosed in U.S. Pat. No. 4,417,439 granted to D. Sepulveda et al on Nov. 29, 1983 entitled "Starting Means for a Gas Turbine Engine" and U.S. Pat. No. 4,785,623 granted to H. G. Reynolds on Nov. 22, 1988 entitled "Combustor Seal and Support", both of which are commonly assigned to United Technologies Corporation, the assignee of this patent application and both incorporated by reference herein. In the 4,417,439 patent, supra, the ignition was improved upon by incorporating restrictors in the fuel lines connecting each of the fuel nozzles except the ones located adjacent the igniter. In that instance, the fuel flow in each of the restricted nozzles was reduced leaving additional fuel of the total for the unrestricted fuel nozzle. Again, because the swirler distance to the primary nozzle was close enough this presented an entirely different problem from the one confronting applicant.